Have you told them how much you dislike track? Why do they push you towards track so much? Was one of your parents a former track star? Do they think that there is potentially a college scholarship in your future? I would sit down and come up with a list of pros and cons about you joining this team and what it would add to your life. Real legit reasons that are thought out and mature (might want to throw in that you care about it enough to agree to pay off a bike). Then present them with this list and your adult discussion. Basically, surprise them with how mature you're being. If nothing else this should at least get you into a conversation that you can hopefully work your way through from there.